How to install and configure Varnish with Apache on Centos 7

Varnish is an open source reverse HTTP proxy, an web accelerator typically run in front of web servers such as Apache or Nginx. Designed to increase the performance of busy, dynamic web sites in case of high server traffic.

In this article, i will explain how to install and configure Varnish as a front-end to an Apache web server on Centos 7 .

Environment

– A Centos 7 Server running Apache

Step 1 – Add EPEL Repository

Before installing Varnish we need to install the EPEL Release using the follow command

[root@webserver ~]# yum install epel-release -y

 

Step 2 – Install Varnish

[root@webserver ~]# yum update -y 
[root@webserver ~]# yum install varnish -y

 
After Installing Varnish we need to start and enable Varnish to start at boot using the following commands

[root@webserver ~]# systemctl enable varnish  
[root@webserver ~]# systemctl start varnish

 

Step 3 – Varnish Configuration

By default Varnish listens on port 6081. So we need to change port 6081 to 80 by editing the varnish.params config file.

[root@webserver ~]# vi /etc/varnish/varnish.params  

 
Change VARNISH_LISTEN_PORT from 6081 to 80:

VARNISH_LISTEN_PORT=80

 

Now open the default.vcl file and configure the port of your backend web server :

[root@webserver ~]# vi /etc/varnish/default.vcl 

 
Change the port to 8080.

backend default {
.host = "127.0.0.1";
.port = "8080";
}

 

Step 4 – Apache Configuration

By default Apache listens on port 80. Now, we need to replace the default Apache port to 8080.

[root@webserver ~]# vi /etc/httpd/conf/httpd.conf

 

Listen 8080

 

After that we need to restart httpd and varnish using the following commands

[root@webserver ~]# systemctl restart httpd
[root@webserver ~]# systemctl restart varnish

 

Step 5 – Test Varnish

To verify that Varnish is on and working properly, you can use the curl command to view the HTTP header:

[root@webserver ~]# curl -I http://localhost

 
You should get an output like this

HTTP/1.1 200 OK
Date: Mon, 14 Nov 2016 12:21:07 GMT
Server: Apache
Content-Length: 108
Content-Type: text/html; charset=UTF-8
X-Varnish: 32807
Age: 0
Via: 1.1 varnish-v4
Connection: keep-alive